Sensitivity and specificity of color duplex ultrasound measurement in the estimation of internal carotid artery stenosis: a systematic review and meta-analysis

BACKGROUND: Duplex ultrasound is widely used for the diagnosis of internal carotid artery stenosis. Standard duplex ultrasound criteria for the grading of internal carotid artery stenosis do not exist; thus, we conducted a systematic review and meta-analysis of the relation between the degree of internal carotid artery stenosis by duplex ultrasound criteria and degree of stenosis by angiography. METHODS: Data were gathered from Medline from January 1966 to January 2003, the Cochrane Central Register of Controlled Trials and Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, ACP Journal Club, UpToDate, reference lists, and authors' files. Inclusion criteria were the comparison of color duplex ultrasound results with angiography by the North American Symptomatic Carotid Endarterectomy Trial method; peer-reviewed publications, and >/=10 adults. RESULTS: Variables extracted included internal carotid artery peak systolic velocity, internal carotid artery end diastolic velocity, internal carotid artery/common carotid artery peak systolic velocity ratio, sensitivity and specificity of duplex ultrasound scanning for internal carotid artery stenosis by angiography. The Standards for Reporting of Diagnostic Accuracy (STARD) criteria were used to assess study quality. Sensitivity and specificity for duplex ultrasound criteria were combined as weighted means by using a random effects model. The threshold of peak systolic velocity >/=130 cm/s is associated with sensitivity of 98% (95% confidence intervals [CI], 97% to 100%) and specificity of 88% (95% CI, 76% to 100%) in the identification of angiographic stenosis of >/=50%. For the diagnosis of angiographic stenosis of >/=70%, a peak systolic velocity >/=200 cm/s has a sensitivity of 90% (95% CI, 84% to 94%) and a specificity of 94% (95% CI, 88% to 97%). For each duplex ultrasound threshold, measurement properties vary widely between laboratories, and the magnitude of the variation is clinically important. The heterogeneity observed in the measurement properties of duplex ultrasound may be caused by differences in patients, study design, equipment, techniques or training. CONCLUSIONS: Clinicians need to be aware of the limitations of duplex ultrasound scanning when making management decisions.     

Correlation of transcranial Doppler and noninvasive tests with angiography in the evaluation of extracranial carotid disease

To evaluate the usefulness of transcranial Doppler sonography in determining severity of extracranial carotid disease, we compared transcranial Doppler, ocular pneumoplethysmography, Doppler spectral analysis, and duplex scanning data to information derived from cerebral angiography. Fifty-one consecutive patients with unilateral extracranial internal carotid artery stenosis or occlusion were selected. Transcranial Doppler indexes included the peak systolic flow velocity in the middle cerebral artery ipsilateral to the stenosed internal carotid artery (iMCAFV), the difference between the peak systolic flow velocities in the middle cerebral artery ipsilateral and contralateral to the stenosed internal carotid artery (dMCAFV), and the peak systolic flow velocity in the anterior cerebral artery contralateral to the stenosed internal carotid artery (cACAFV). The minimal residual lumen determined angiographically was used as the index of internal carotid artery stenosis. Linear regression analysis with minimal residual lumen as the dependent variable and transcranial Doppler and noninvasive tests as independent variables showed the following correlation coefficients: (1) dMCAFV and cACAFV, R2 = 0.3170; (2) ocular pneumoplethysmography, R2 = 0.4798; (3) dMCAFV, cACAFV, delta ocular pneumoplethysmography, duplex scanning, and spectral analysis R2 = 0.6382; (4) ocular pneumoplethysmography, duplex scanning, and spectral analysis, R2 = 0.6491; (5) iMCAFV, no association. These results were supported by sensitivity and specificity as well as bivariate analysis. We conclude that transcranial Doppler did not significantly add to the information obtained by our noninvasive battery of tests in the evaluation of unilateral extracranial carotid disease.     

Comparison of color-flow Doppler scanning, power Doppler scanning, and frequency shift for assessment of carotid artery stenosis

OBJECTIVE: We investigated the accuracy of color-flow Doppler (CD) scanning, power Doppler (PD) scanning, and peak systolic Doppler frequency shift (PSF) in assessment of carotid artery stenosis with angiography used as gold standard, including the measurement techniques used in the North American Symptomatic Carotid Surgery Trial (NASCET) and the European Carotid Surgery Trial (ECST). METHODS: Fifty-eight consecutive patients diagnosed for carotid artery surgery underwent color-coded duplex sonography and angiography. The duplex examination included the assessment of PSF and the videotaping of sagittal images in CD and PD mode from the proximal common carotid artery to the distal internal carotid artery. Two experienced examiners performed the studies, but once one examiner had done the taping, the other examiner was allowed only to review the tape. Separately, each examiner reviewed the tapes and determined by cursor settings each stenosis according to NASCET and ECST. For interobserver agreement kappa statistic was used. To compare with angiography (degree of stenosis 40%, 50%, 60%, 70%, and 80%) sensitivity, specificity, positive and negative predictive values, and overall accuracy were calculated. PSF cut-off frequencies were based on receiver operator curve analysis. RESULTS: Because interobserver agreement in CD and PD was good (chance-corrected kappa > 0.6), further analysis used the between-observer mean value for each stenosis. With the NASCET measurement technique, accuracy of Doppler techniques to distinguish a 50% stenosis was 89% for PSF, 91% for CD, and 93% for PD; for a 70% stenosis it was 83% for PSF, 84% for CD, and 81% for PD. With the ECST measurement technique, accuracy to distinguish a 70% stenosis was 86% for PSF, 88% for CD, and 86% for PD; for an 80% stenosis it was 87% for PSF, 87% for CD, and 77% for PD. CONCLUSION: CD and PD carotid artery stenosis measurements are highly reproducible, and in our hands provided accuracy equal to PSF.     

Reproducibility of transcutaneous continuous-wave Doppler testing of the carotid arteries

Hand-held, continuous-wave Doppler probes, coupled with sound spectral analysis, can successfully predict carotid artery stenosis. Changing either the emitting frequency of the probe, the beam/artery angle of the carotid flow velocity (e.g. cardiac output) may alter the recorded frequency shifts. These effects raise questions as to the efficacy of this technique to serially follow carotid atheroma for progressive stenosis. To test the inherent problems with this methodology, a study of reproducibility was conducted. Two Doppler probes (5 MHz and 8 MHz) were compared at the same sitting in 24 patients; 12 were restudied on two subsequent occasions. Peak systolic frequency was 135% higher with the 8 MHz probe; this was lower than the 160% calculated by substitution for emitting frequency in the Doppler formula. The linear correlation coefficient of the two probes was 0.88. In relationship to established laboratory criteria of a >75% area stenosis, no errors were noted with the 5 MHz probe while four errors were noted with the 8 MHz probe. A serial study variation of peak systolic frequency was noted for both probes; these variations did not cross established criteria levels of a severe stenosis when the 5 MHz probe was used, but did with the 8 MHz probe for two carotids. A standard examining probe is recommended. Angle and cardiac output changes do result in peak systolic frequency variation from test to test, but these were not clinically significant with the 5 MHz probe. Thus, significant changes during follow-up testing should provide an index of evolving carotid stenosis.     

The effect of unilateral internal carotid arterial occlusion upon contralateral duplex study: criteria for accurate interpretation.

To determine the influence of unilateral internal carotid arterial occlusion (ICO) on Doppler frequency spectral analysis (DFSA) of the patent contralateral carotid artery, a retrospective review of 154 patients between July 1987 and December 1991 with angiographically confirmed ICO was performed, correlating duplex and arteriographic findings in a blinded fashion. Biplane arteriograms and bilateral carotid artery duplex studies that used a 5.0 MHz Doppler probe with a 1.5 mm3 sample volume at a 60 degree angle of insonation were performed on all patients. Each carotid artery was categorized by the severity of stenosis as quantified by arteriography: 1% to 15% (n = 41); 16% to 49% (n = 48), 50% to 79% (n = 21), 80% to 99% (n = 34), and bilateral occlusion (n = 10). DFSA peak systolic frequencies were commonly exaggerated in the presence of contralateral ICO and use of standard criteria for DFSA interpretation overestimated bifurcation stenoses in 43 of 89 lesions (48.3%) when determining nonhemodynamically significant lesions (less than 50% diameter reduction) with a sensitivity of only 57.3% and specificity of 96.9%. Conversely, prediction of hemodynamically significant lesions (greater than 50% diameter reduction) with standard criteria had 96.9% sensitivity but only 57.3% specificity. Modification of these criteria to account for the velocity increase or "jet effect" in the ipsilateral carotid artery system increased the sensitivity and specificity to 97.8% in predicting nonhemodynamically and hemodynamically significant stenoses respectively. A Doppler frequency spectrum with a peak systolic frequency (PSF) greater than 4.0 kHz and end-diastolic frequency (EDF) less than 5 kHz with an "open window" distinguished lesions with less than 50% diameter reduction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Follow-up of stented carotid arteries by Doppler ultrasound

OBJECTIVE: Blood flow velocity (BFV) in the carotid artery is altered by stent placement. The significance of these alterations is unknown. In our experience, both standard BFV criteria for stenosis and customized criteria recommended by other authors have led to high rates of false-positive studies. We reviewed our experience with Doppler ultrasonography immediately after extracranial carotid artery stent placement to define criteria for restenosis by BFV. METHODS: Complete carotid angiograms and BFV results were available for 114 patients treated between January 1998 and December 1999. Angiographic images obtained immediately after stent placement and at follow-up were measured for residual or recurrent stenosis by a blinded reviewer according to the North American Symptomatic Carotid Endarterectomy Trial method. Results of BFV studies obtained within 1 week of stent placement were interpreted by using two standard criteria (A, peak in-stent systolic velocity greater than 125 cm/s; B, internal carotid artery-to-common carotid artery ratio greater than 3.0) and two customized criteria (C, peak in-stent velocity greater than 170 cm/s; D, internal carotid artery-to-common carotid artery ratio greater than 2.0). The results of follow-up angiography and the most recent Doppler study were compared for nine patients. RESULTS: On the basis of an examination of Doppler studies obtained immediately after stent placement, 36 patients met Criterion A for stenosis according to measured BFV (corresponding mean angiographic stenosis, 14.73 +/- 18.45%), 3 patients met Criterion B (mean stenosis, 1.67 +/- 2.89%), 8 patients met Criterion C (mean stenosis, 12.61 +/- 13.18%), and 14 met Criterion D (mean stenosis, 7.98 +/- 21.74%). No patient with Doppler criteria for significant stenosis had more than 50% residual stenosis. Three of nine patients who underwent follow-up angiography had stenosis of 50% or more; of these three patients, two underwent second angioplasty procedures. The peak in-stent systolic velocity or internal carotid artery-to-common carotid artery BFV ratio for each of the three patients with restenosis, but not for the six other patients, had increased by more than 80% since the immediate post-stenting Doppler study. CONCLUSION: Strict BFV criteria for restenosis after carotid artery stenting are less reliable than change in BFV over time. An immediate post-stenting Doppler study must be obtained to serve as a reference value for future follow-up evaluation.     

大鼠颈总动脉端端吻合术后的血流动力学动态观察

研究小动脉端端吻合术后血流动力学变化，为进一步的研究提供依据。选用ＳＤ大鼠１０只，切断左侧颈总动脉行端端吻合。术后６，１２，２４，４８，７２和１２０小时，用彩色多普勒血流仪经皮连续测定实验侧颈总动脉吻合口近端、吻合口、吻合口远端，以及对照侧颈总动脉的收缩期最高血流速度，计算吻合口横切面的狭窄面积百分比。结果显示，术后各个时间段，吻合口收缩期最高血流速度均明显高于吻合口近端、吻合口和对照侧颈总动脉的血流速度（Ｐ＜０．０５）；吻合口远端的收缩期血流速度均低于吻合口近端和对照侧颈总动脉的血流速度（Ｐ＜０．０５），血流速度分别降低３３．１８％和３３．３３％。术后６小时～１２０小时均出现不同程度的狭窄，平均减少４２．４８％。认为，小动脉端端吻合术后６小时～１２０小时，吻合口血流速度均明显高于吻合口近端和吻合口远端的血流速度；吻合口远端的流速均明显低于吻合口近端的流速；吻合口及其近、远端的血流速度变化不一致。     

Carotid Doppler velocity measurements and anatomic stenosis: correlation is futile

Background: Duplex ultrasound with Doppler velocimetry is widely used to evaluate the presence and severity of internal carotid artery stenosis; however, a variety of velocity criteria are currently being applied to classify stenosis severity. The purpose of this study is to compare published Doppler velocity measurements to the severity of internal carotid artery stenosis as assessed by x-ray angiography in order to clarify the relationship between these 2 widely used approaches to assess carotid artery disease. Methods: Scatter diagrams or "scattergrams" of correlations between Doppler velocity measurements and stenosis severity as assessed by x-ray contrast angiography were obtained from published articles for native and stented internal carotid arteries. The scattergrams were graphically digitized, combined, and segmented into categories bounded by 50% and 70% diameter reduction. These data were combined and divided into 3 sets representing different velocity parameters: (1) peak systolic velocity, (2) end-diastolic velocity, and (3) the internal carotid artery to common carotid artery peak systolic velocity ratio. The horizontal axis of each scattergram was transformed to form a cumulative distribution function, and thresholds were established for the stenosis categories to assess data variability. Results: Nineteen publications with 22 data sets were identified and included in this analysis. Wide variability was apparent between all 3 velocity parameters and angiographic percent stenosis. The optimal peak systolic velocity thresholds for stenosis in stented carotid arteries were higher than those for native carotid arteries. Within each category of stenosis, the variability of all 3 velocity parameters was significantly lower in stented arteries than in native arteries. Conclusion: Although Doppler velocity criteria have been successfully used to classify the severity of stenosis in both native and stented carotid arteries, the relationship to angiographic stenosis contains significant variability. This analysis of published studies suggests that further refinements in Doppler velocity criteria will not lead to improved correlation with carotid stenosis as demonstrated by angiography.     

The hemodynamic effects of internal carotid artery stenosis and occlusion

The purpose of this study was to determine in subhuman primates whether hemodynamic mechanisms (as compared with embolic mechanisms) contribute to cerebral ischemia following carotid artery occlusion or stenosis. Following carotid artery occlusion there was loss of cerebral autoregulation: cerebral blood flow (CBF) measured with the xenon-133 technique became passively dependent upon the mean arterial blood pressure (MABP) over an MABP range of 30 to 110 mm Hg. By contrast, autoregulation was preserved in normal animals and in animals with a 90% carotid artery stenosis. Regional CBF was measured with carbon-14-labeled iodoantipyrine autoradiography in normotensive baboons, in hypotensive animals, and in hypotensive animals with carotid artery occlusion or stenosis. With carotid artery occlusion and hypotension, reduced levels of local CBF were seen ipsilaterally in the boundary zones between the anterior and middle cerebral arteries with 35% of the area of an anterior section through the hemisphere displaying a CBF value of less than 20 ml/100 gm/min. Comparable values with hypotension were 21% with carotid artery stenosis, 20% with no proximal vascular lesion, and 1% in normotensive animals. These areas of reduced CBF corresponded with areas of boundary-zone ischemia seen with light microscopy. The study suggests that while hemodynamic ischemia develops with carotid artery occlusion, it does not occur with even a 90% carotid artery stenosis or in normal animals.     

Effect of carotid endarterectomy on chronic ocular ischemic syndrome due to internal carotid artery stenosis

OBJECTIVE: We evaluated the effect of carotid endarterectomy on chronic ocular ischemic syndrome due to internal carotid artery stenosis by use of data obtained from ophthalmic artery color Doppler flow imaging. METHODS: We examined 11 patients with ocular ischemic syndrome due to internal carotid artery stenosis (>70% stenosis) who were being treated by carotid endarterectomy. Ophthalmic artery color Doppler flow imaging indicated ophthalmic artery flow direction and peak systolic flow velocity and was performed before and at 1 week, 1 month, and 3 months after surgery. RESULTS: We assessed the ophthalmic arteries of 11 patients via color Doppler flow imaging. Before undergoing carotid endarterectomy, five patients showed reversed ophthalmic artery flow. In the other six patients who experienced antegrade ophthalmic artery flow, the average peak systolic flow velocity was 0.09 +/- 0.05 m/s (mean +/- standard deviation). Preoperative reversed flow resolved in each patient 1 week after undergoing surgery. All patients showed antegrade ophthalmic artery flow. The average peak systolic flow velocity in the patients who had preoperative antegrade flow rose significantly, to 0.21 +/- 0.14 m/s (P < 0.05). There was no significant change as compared with findings at 1 week after surgery. During the follow-up period (mean, 32.4 mo), no patients complained of recurrent visual symptoms. At the end of the study period, visual acuity had improved in five patients and had not worsened in the other six patients. CONCLUSION: Carotid endarterectomy was effective for improving or preventing the progress of chronic ocular ischemia caused by internal carotid artery stenosis.     

Carotid surgery without arteriography: Noninvasive selection of patients

All carotid noninvasive studies at our institution comprised of duplex scanning, spectral frequency analysis, and ocular-pneumoplethysmography-Gee supraorbital Doppler assessments from 1985–1987 were reviewed. Forty symptomatic and 104 asymptomatic internal carotid arteries, concomitantly studied noninvasively and arteriographically, were identified. All studies were rereviewed prospectively and in blinded fashion. Utilizing peak frequency—internal carotid artery >10 mHz and carotid index (Pf-ICA)/PF-common carotid) >5 as criteria for surgery, 39/40 symptomatic internal carotid arteries were considered appropriate for carotid endarterectomy by noninvasive study. All of these internal carotid arteries had arteriographic confirmation of >50% internal carotid artery stenosis; 22 of them met noninvasive criteria for surgery of peak systolic frequency-internal carotid artery 14 mHz, carotid index >7 and abnormal ocular-pneumoplethysmography-Gee supraorbital Doppler. All of these had arteriographic confirmation of >80% internal carotid artery stenosis. Eleven asymptomatic internal carotid arteries met spectral frequency criteria for carotid endarterectomy but had normal ocular-pneumoplethysomgraphy-Gee/supraorbital Doppler. Eight in this group had <80% stenosis on arteriographic exam. Carotid endarterectomy may be performed without prior arteriography, provided objective criteria are established in a reliable noninvasive lab and met by individual patients. Presented at the Annual Meeting of the Eastern Vascular Society, Southhampton, Bermuda, May 5, 1989.     

Effect of carotid endarterectomy on the ophthalmic artery

Summary. Summary.   Background: To evaluate the effect of carotid endarterectomy on ophthalmic artery flow direction and peak systolic flow velocity, the authors examined the ophthalmic artery on 32 patients who had undergone carotid endarterectomy.   Methods: The 32 patients had more than 70% stenosis of the internal carotid artery at its origin on angiography. The ophthalmic artery ipsilateral to the carotid endarterectomy was evaluated by the ophthalmic artery color Doppler flow imaging before surgery and then at one week, one month, and three months after surgery.   Findings: (1) Before carotid endarterectomy: eight patients showed reversed ophthalmic artery direction. In the other 24 patients with antegrade ophthalmic artery flow direction, the average peak systolic flow velocity was 0.17±0.10 m/sec. (2) At one week after carotid endarterectomy: The reversed ophthalmic artery flow direction was resolved in each patient. The average peak systolic flow velocity in the patients with preoperative antegrade flow rose significantly to 0.28±0.10 m/sec (p<0.05). (3) At one month and three months after carotid endarterectomy: All patients showed the antegrade ophthalmic artery flow direction. The average peak systolic flow velocities showed no significant change compared to the value at one week after carotid endarterectomy. (4) During the followed up period, there was no patient showing worsening or recurrence of clinical symptoms including the visual symptoms.   Interpretation: Carotid endarterectomy brought about the correction of the reversed flow and an increase in the peak systolic flow velocity of the ipsilateral ophthalmic artery immediately after surgery.     

Prospective evaluation of new duplex criteria to identify 70% internal carotid artery stenosis

Purpose: Large multicenter trials (North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial) have documented the benefits of carotid endarterectomy for treating symptomatic patients with ≥70% stenosis of the internal carotid artery. Although color-flow duplex scanning has become the preferred method for noninvasive assessment of internal carotid artery disease, no criteria have been generally accepted to identify this subset of patients. We previously reported a retrospective series to establish such criteria. This study details our results when these criteria were applied prospectively.Methods: Carotid color-flow duplex scans were compared with arteriograms in 457 patients who underwent both studies. Criteria for ≥70% internal carotid artery stenosis were peak systolic velocity >130 cm/sec and end-diastolic velocity >100 cm/sec. Internal carotid arteries with peak systolic velocity <40 cm/sec in which only a trickle of flow could be detected were classified as preocclusive lesions (95% to 99% stenosis). Arteriographic stenosis was determined by comparing the diameter of the internal carotid artery at the site of maximal stenosis to the diameter of the normal distal internal carotid artery.Results: Internal carotid artery stenosis of ≥70% was detected with a sensitivity of 87%, specificity of 97%, positive predictive value of 89%, negative predictive value of 96%, and overall accuracy of 95%. Eighty-seven percent of 70% to 99% stenoses were correctly identified. False-positive errors (n = 10) were attributed to contralateral internal carotid artery occlusion or high-grade (>90%) stenosis (n = 5) and to interpreter error (n = 1); no explanation was apparent in the other four. Eleven of 12 false-negative examinations occurred in patients with 70% to 80% internal carotid artery stenosis.Conclusions: In our laboratories, prospective application of the above velocity criteria identified internal carotid artery stenosis of ≥70% with a reasonably high degree of accuracy. Errors occurred when stenoses were borderline and in patients with severe contralateral disease. With suitably modified velocity criteria, color-flow duplex scanning remains the most reliable noninvasive method for identifying symptomatic patients who are candidates for carotid endarterectomy. (J V ASC S URG 1996;23:254-62.)     

Pulsed Doppler frequency and carotid stenosis

Two hundred and forty-two internal carotid arteries (ICA) were evaluated by independently interpreted arteriography and pulsed Doppler spectrum analysis using ultrasonic arteriography to evaluate the ability of peak systolic frequency (PSF) to predict the degree of internal carotid stenosis. Mean PSF in the 129 (53.3%) high grade ICA stenoses of greater than 50% diameter reduction was 6.55 +/- 0.14 (SEM) khz, while mean PSF in the 113 (46.7%) low grade (less than 50% diameter reduction) stenoses was 3.38 +/- 0.12 (SEM) kHz (P less than 0.0001). Receiver-operator characteristic (ROC) analysis revealed that PSFs of 4.5 kHz (sensitivity 87%, specificity 88%) and 5.0 kHz (sensitivity 83%, specificity 93%) were best for identifying a 50% diameter stenosis. Positive predictive value of 5.0 kHz was 93% (107/115) and negative predictive value was 82.7% (105/127). Linear regression analysis of PSF in kHz versus percentage diameter reduction yielded the equation: % stenosis = 10.7 (PSF) - 4.1 (r = 0.76). A nonlinear equation was also derived: % stenosis = 61.9 - 33.5 (PSF) + 8.7 (PSF)2 - 0.5 (PSF)3 (r = 0.77). Based on this analysis peak systolic frequency criteria measured by pulsed Doppler spectrum analysis appear to be useful for distinguishing high grade from low grade stenoses. Both the linear and nonlinear equations further suggest that PSF can more precisely quantitate the degree of ICA luminal narrowing.     

Study of cavernosal arterial anatomy using color and power Doppler sonography: impact on hemodynamic parameter measurement.

PURPOSE: We report on color and power Doppler ultrasound to study cavernosal arterial anatomy, and evaluate the impact of vascular anatomy on the measurement of hemodynamic parameters. MATERIALS AND METHODS: Cavernosal arterial anatomy of 42 patients with erectile dysfunction was evaluated using color and power Doppler ultrasound. A computerized waveform analysis was used to measure peak systolic velocity, end diastolic velocity and resistive indexes at various sites, including the penile crura, and proximal mid and distal penile shaft. Hemodynamic parameters were measured in each artery in cases of bifurcated or multiple cavernosal arteries. RESULTS: A total of 80 corpora were adequately evaluated. We observed a single artery without major proximal branches in 37 corpora, a single artery with major proximal branches in 17, bifurcated arteries in 15, 2 cavernosal arteries in 4 and marked arterial tortuosity in 1. In 6 corpora the main cavernosal artery arose from the superficial dorsal artery. The peak systolic velocity was highest at the proximal and decreased progressively at the distal site. The peak systolic velocity plus or minus standard deviation at the mid shaft averaged 69.3+/-30.0% of that at the proximal penile shaft. Of the 15 corpora with bifurcated arteries 67% had a 40% or greater difference in peak systolic velocity between the branches. Complete or partial occlusion of the cavernosal artery was identified in 3 corpora, and a dramatic difference in peak systolic velocity proximal and distal to the stenotic area was demonstrated. CONCLUSIONS: Cavernosal arterial anatomy is variable and hemodynamic parameters differ at various sites of measurement. Parameters should be measured at a consistent proximal site to obtain a reliable assessment. Variations in vascular anatomy and cavernosal artery pathology should be considered when interpreting color Doppler sonography and before penile vascular surgery.     

Carotid-subclavian bypass and the carotid steal phenomenon

Twelve patients with patent carotid-subclavian bypass grafts were investigated by colour flow duplex imaging to look for a carotid steal. Centre-stream peak systolic flow velocities in the common carotid arteries distal to the take-off of the bypass graft were equivalent to those in the contralateral common carotid artery. On the side of the bypass, common carotid flow proximal to the graft was almost double that on the distal side. Steal phenomena were not identified in the carotid artery either with the arm at rest or during hyperaemia. However, in two instances arm hyperaemia caused reversal of flow in the ipsilateral vertebral artery, suggesting the induction of a subclavian steal. The method of centre-stream peak systolic velocity as an index of flow confirmed that carotid-subclavian bypass can be safely carried out without depriving the cerebral circulation of the normal carotid inflow.     

Transcranial Doppler ultrasound in internal carotid artery and middle cerebral artery disease

Using noninvasive transcranial Doppler sonography, we studied cerebral collateral patterns in 30 patients with stenosis and/or occlusion of the extracranial internal carotid artery (ICA). All patients with unilateral ICA stenosis ⩽ 80% had normal transcranial Doppler findings. 80% of patients with unilateral and 50% of patients with bilateral ICA stenosis of more than 80% including those with occlusion showed a collateralization via the ipsilateral anterior and/or posterior cerebral artery. 20% of patients with unilateral and 50% of patients with bilateral ICA stenoses of more than 80% (including occlusion) had two or three collateral pathways, including the ophthalmic artery. Another ten patients with stenosis or spasm of the middle cerebral artery (MCA) showed increased flow velocities with turbulence in the narrow segment. In four patients with severe MCA disease with a systolic peak velocity of more than 200 cm/s, the Doppler waveform distal to the lesion was damped. Decreased regional cerebral blood flow (rCBF) measured by^99mTc-HMPAO-SPECT was found in two patients with severe MCA stenosis. Another patient with moderate MCA stenosis with a systolic peak velocity of 140 cm/s showed a normal cerebral perfusion pattern.     

The contribution of spectral analysis to the diagnosis of carotid artery disease

Pulsed and continuous-wave Doppler examinations with spectral analysis were performed on 258 carotid arteries in 220 patients and compared with multiplane contrast angiography. Each artery was examined for stenosis and assigned to one of four groups: normal to 19%, 20% to 49%, 50% to 99%, and occlusion. The incidence of disease was 70%. Diagnostic sensitivity with all noninvasive techniques varied from 76% to 90% depending on the degree of stenosis, with an overall accuracy rate of 86%. In an attempt to evaluate the diagnostic contribution of spectral analysis, stenosis classification by peak frequency alone was compared with that of the full laboratory profile, including spectral analysis. In the 147 carotid arteries in which such data were available, diagnostic sensitivity was improved with spectral analysis by 8% to 29% depending on the degree of stenosis. Detection of occlusions was unchanged. The major contribution of spectral analysis was in detecting non-flow-limiting stenoses of 20% to 49%. Spectral analysis added little to the diagnostic ability of peak frequency to detect lesions with greater than 50% stenosis. Spectral analysis of either pulsed Doppler or continuous-wave Doppler signals is an accurate noninvasive method for evaluating carotid bifurcation disease, which particularly improves the detection of non-flow-limiting stenoses.     

Mesenteric artery disease in the elderly

PURPOSE: The purpose of this study was to estimate the population-based prevalence of mesenteric artery stenosis (MAS) and occlusion among independent elderly Americans. METHOD: As part of an ancillary investigation to the Cardiovascular Health Study (CHS), participants in the Forsyth County, NC cohort had visceral duplex sonography of the celiac arteries and superior mesenteric arteries (SMAs). Critical MAS was defined by celiac peak systolic velocity >or=2.0 m/s and/or SMA peak systolic velocity >or=2.7 m/s. Occlusion of either vessel was defined by lack of a Doppler-shifted signal within the imaged artery. Demographic data, blood pressures, and blood lipid levels were collected as part of the baseline CHS examination. Participants' weights were measured at baseline and before the duplex exam. Univariate tests of association were performed with two-way contingency tables, Student t tests, and Fisher exact tests. Multivariate associations were examined with logistic regression analysis. RESULTS: A total of 553 CHS participants had visceral duplex sonography technically adequate to define the presence or absence of MAS. The study group had a mean age of 77.2 +/- 4.9 years and comprised 63% women and 37% men. Participant race was 76% white and 23% African-American. Ninety-seven participants (17.5%) had MAS. There was no significant difference in age, race, gender, body mass index, blood pressure, cholesterol, or low-density lipoproteins for participants with or without MAS. Forward stepwise variable selection found renal artery stenosis (P =.008; odds ratio [OR], 2.85; 95% confidence interval [CI], 1.31, 6.21) and high-density lipoprotein >40 (P =.02; OR, 3.03; 95% CI, 1.17, 7.81) significantly associated with MAS in a multivariate logistic regression model. Eighty-three of the 97 participants with MAS (15.0% of the cohort) had isolated celiac stenosis. Seven participants (1.3% of the cohort) had combined celiac and SMA stenosis. Five participants (0.9% of the cohort) had isolated SMA stenosis. Two participants (0.4% of the cohort) had celiac occlusion. Considering all participants with MAS, there was no association with weight change. However, SMA stenosis and celiac occlusion demonstrated an independent association with annualized weight loss (P =.028; OR, 1.54; 95% CI, 1.05, 2.26) and with renal artery stenosis (P =.001; OR, 9.48; 95% CI, 2.62, 34.47). CONCLUSION: This investigation provides the first population-based estimate of the prevalence of MAS among independent elderly Americans. MAS existed in 17.5% of the study cohort. The majority had isolated celiac disease. SMA stenosis and celiac artery occlusion demonstrated a significant and independent association with weight loss and concurrent renal artery disease.     

Grading of internal carotid artery stenosis: validation of Doppler/duplex ultrasound criteria and angiography against endarterectomy specimen.

OBJECTIVES: duplex ultrasound has replaced angiography prior to carotid endarterectomy (CEA) in many institutions. However, the indications for CEA are based on angiographically controlled studies and widely accepted ultrasound criteria do not exist. Consequently, the reliability of Doppler and/or duplex ultrasound to predict a high-grade ICA stenosis has to be proven. DESIGN: prospective validation study. MATERIALS: one hundred and fifty carotid bifurcations assessed by ultrasound and selective angiography and 68 acrylat outcasts of carotid specimen after eversion CEA. METHODS: ICA stenosis was measured angiographically according to the ECST criteria. Combined Doppler acoustic standard criteria (CDASC), peak systolic frequency (PSF), peak systolic velocity (PSV) and end-diastolic velocity (EDV) served as criteria for the ultrasound assessment. These criteria and the results of angiography were compared to the degree of ICA stenosis determined by specimen measurements. RESULTS: the median degree of ICA stenosis as assessed by angiography (82%, range 56-97%) and CDASC (83%, range 50-99%) corresponded well to the specimen measurements (80%, range 50-95%). The sensitivity of angiography and CDASC to predict a 70-90% ICA stenosis (ECST criteria) compared to the specimen measurements was 88% and 95%, respectively. The positive predictive value (PPV) reached 92% and 96%, respectively. CDASC were equivalent to angiography and were superior to the best single frequency or velocity parameters. If CDASC do not indicate a >/=70% ICA stenosis in spite of a PSV >/=180 cm/s and/or an EDV >/=50 cm/s, angiography may detect patients with a >70% ICA stenosis. CONCLUSIONS: CDASC are valid in the quantification of high-grade ICA stenosis. They are more reliable than single velocity and/or frequency measurements. However, if velocity criteria and CDASC do not agree, angiography should be performed.